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Lithium v AGM


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12 hours ago, idlerboat said:

Commercially graded AGMs have a 20 year constant use design time.

This is misunderstood by so many. It relates to the internal connection between the plates and the ability to withstand corrosion. This is never explained by any manufacturer and the figure is very misleading. If the battery is never ever cycled, then it should last 20yrs before the internal inter-plate connections are not longer viable. The more expensive names tend to use very good corrosion resistant materials. However, cheaper manufacturers now also use similar materials and use this figure of longevity as a false positive feature in their claims. In fact I have come across several people that have thought their Battery was designed to last 20yrs when cycled. Which simply is not true. Cycle rates are still the best measure between any make of battery and the more expensive the Battery, the better that cycle number ( for same apple to apple battery type of course).

In my opinion, the best choice of Battery is the Lead Carbon design. Providing weight is not an issue. Some makes are providing cycle rates nearly as high as Li and the cheaper ones are still producing cycle rates 3 times that of standard FLA.
The problem with AGM and Gel is that you need to get a battery designed specifically for Deep cycle and that is in fact very hard to do. Most of these two, most especially the Gel types, is that they are mostly designed for Standby or UPS work. Meaning they are designed to stay trickle charged for extended periods of time without the need of equalisation charging and then be used in a deep cycle providing backup power. But their cycle rates are not so great.

Lithium batteries (of the type we would be using..there are dozens of different types) should have battery management built into the Battery itself. It should be monitoring every cell as it charges.
The issue with the Lithium batteries that have caught fire is due to a condition that the Cadnium batteries had. Filiments grow in the internals and eventually short out the cell. The poblem with the Lithium battery is that the short will then cause severe and sudden overheating and result in the thing exploding in flames. But there are now Lithium designs that are stopping this problem from occuring.

Unless weight is really important, I think it is really hard to justify the expense of LiFePo technology.

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20 hours ago, idlerboat said:

Not to nit pick....but I can get a 200amp AGM for $335 retail....

That changes the dollar per usable for the AGMs to $5.58.......

Commercially graded AGMs have a 20 year constant use design time. "Cycles" as such,  is very hard to quantify. The actual percentage of discharge before a recharge event may be anywhere from a percentage of 1% to the full 30% (assuming that your system has a system regulator that wont allow it to discharge any further.) This of course is the same for any battery system in a boat.

High end and proper charging for LiFePo4 should have a temperature sensor on every cell , they are very sensitive to charge irregularities...

The biggest (and only ) advantage at the moment (and its a big advantage if you want to race or have a lighter displacement boat)  is the weight savings.

 

LiFePo4 doesn't need temp sensors per cell.   Below 0 degree Celsius you generally should not charge them or you will risk the formation on dendrites.   You might have confussed that with AGM and other lead acid variants that should have temp compensation built in to their charging algorithms. 

Your other points are not well founded either to be honest...As there are huge charge efficiency advantages with this chemistry, it is vastly safer that flooded lead acid, Much higher discharge rates of efficiency and ability.  There are many boats now running electric galleys using these batteries and running flawlessly with solar and wind as the charge sources.  They are very light as you point out. 

 

This is a proven technology that has been used for a very long time on other fields.  It is relatively new to the boater,  so most are skeptical and have horror stories that are mostly fictional or user error based.  

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I've used a 100ah lifopo4 on a 9m racer cruiser for about 5 years now for two reasons - significant weight savings and high charge efficiency. For me, these outweigh the increased cost. While I admittedly don't have expertise on this, I'm not aware of evidence to support the fire risk concern - there is plenty of guidance out there about how safe lifepo4 technology is, and by now I think we would be hearing more lifepo4 boat fire stories if it was a risk. Will probably get flak from some for saying this....

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12 hours ago, wheels said:

In my opinion, the best choice of Battery is the Lead Carbon design. Providing weight is not an issue. 

I agree its a brilliant technology and perfect in a lot of cases  Lead carbon is very hard to go past and I was on the fence with my battery purchase between those and LiFePo4.    The biggest issue with Lead Carbon is the charge requirements of the technology are less forgiving than LiFePo4, but also they quite specialized....no issue if you have a infinitly variable controller like a Victron smartsolar for example.   However,  the voltage drop when loaded with medium to high loads in 'MY' case was not going to be acceptable.   If you are not going to run big inverters or winches or other high loads...you have the space and can handle the weight....its a no brainer get lead carbon from a reputable manufacturer at about half the price of LiFePo4.  

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The LiFePO4 "fire risk" is a non-event for boats IMHO.  Certainly in a car environment, where you have many many cells and are caning them to push some bloated passengers up a steep hill, can have issues (as in any battery technology) if a cell fails and resistance increases.  In a boat that is simply a non-starter - you only have a few cells and the load and charging amps are an order of magnitude less than the automotive stuff.  Any decent BMS will be looking at cell temperatures, in my install we have  sensors for 8 cells.

And Idlerboat - you will never get 20 years from AGMs in a cruising environment.  They like being topped up and that isn't that comment when you live on them 4/7.  I have had several people tell me their experiences with AGMs dying after 2-3 years.

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On 3/09/2020 at 8:19 PM, Dtwo said:

And Idlerboat - you will never get 20 years from AGMs in a cruising environment.  They like being topped up and that isn't that comment when you live on them 4/7.  I have had several people tell me their experiences with AGMs dying after 2-3 years.

Im not sure what that means ? AGM s do not require any physical (apart from electrical) maintenance.  They can be installed upside down quite happily.

1668199017_Screenshot(9).thumb.png.39642d45159d5248f40943cb30dfb4be.png

 

AGMs  wont last 20 years on a boat ?   :)  maybee... but mine are well on the way. (second hand ex critical infrastructure batteries, now on my boat for 12 years)  I guess we will have to wait for the other chemistry to get a bit older before it can make the same claims...

WIN_20200904_22_05_20_Pro.thumb.jpg.fab3867ccbc8311f2fe23973794a8607.jpg

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This last picture is taken right now to my right...(with the lap top that I am typing this to you on)   : )  no its not on my boat... 

But I just want you to understand that I am not playing...internet stuff.......that is less than a third of the bank I am currently putting in.

And YES 20 years IS the design time for Commercial AGMs. Please read again about cycle parameters. 

I am a super practical person. I have limited finances. SO...Cost. Reliability. Longevity. Proof of product. Appropriate for circumstances .  Thats what I do. / and what I always tell anyone else to do. 

I have no problem with any Lithium tech, and it will be incredibly important . As I said, the only benefit at the moment is weight. It is far from cheaper on any scale you wish.. (amp/ hrs versus $) I say this with no zealotry intent. I wish it was...To say Lithium is proven is quite true. Look around at power tools , and a heap more. Cars for example also. But lets face it..weight is a governing factor here. 

SO.. I let my first post stand. Unless you need weight savings, there is no direct benefit of  lithium tech... (Oh and it is a rare metal)

 

 

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7 hours ago, idlerboat said:
On 3/09/2020 at 10:19 PM, Dtwo said:

And Idlerboat - you will never get 20 years from AGMs in a cruising environment.  They like being topped up and that isn't that comment when you live on them 4/7.  I have had several people tell me their experiences with AGMs dying after 2-3 years.

Im not sure what that means ? AGM s do not require any physical (apart from electrical) maintenance.  They can be installed upside down quite happily.

I think what D2 is meaning is that it is not always Convenient to keep a battery bank fully charged when living on the boat 24/7. And in most instances, no you won't get 20yrs from a AGM. But nor will you from any LA battery type. The life of any battery us simply the number of cycles it can provide. The number of cycles is summed by the depth of discharge.
Longevity between Gel/AGM/FLA is a very difficult one to judge. It is dependent on what the Manufacturer is designing the battery for. No Maintenance batteries lend themselves to Remote Power Backup systems and thus the majority tend to be built for that. But you can get Gel/AGM designed specifically for Deep cycle apps as well and the one designed for such, can actually give a better life that an FLA. But you pay for it.
For instance
Battery Charging Faults - Schaudt Elektroblock, Reich E ...
Please note the difference in the Long Life against their standard Gel.

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idlerboat, as a 'super practical person' i am surprised that you would only see the weight factor as an advantage for lithium batts.  so, here's a couple of things i have found to be fantastic about mine -

- I'm able to stick 125 amps in until they are full 

- they don't need to be fully charged - they are sitting here at present at 58% while I'm on shore power

- battery voltage is incredibly stable throughout the discharge cycle

I'm not interested in changing your mind, but it does help to consider all the factors that affect the choice between different battery technology

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Super capacitors are also an alternative. I know of a number of installations with solar charging. As a technology they are streets ahead of "chemistry" based storage.

They will definitely ramp up in their usage and the price will come down a lot over the next few years. 

Here is a link to a commercially available stand alone power supply .

https://solarbatteriesonline.com.au/product/sirius-energy-storage-capacitor-module-3-55kwh-48v/

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Actually Super Capacitor is a not actually what they are. A true Super or Ultra Capacitor is something quite different. Commonly found in Computers. But also used as regenerative storage devices. They cannot be used for the kind of battery we need, simply because their Voltage is linear to Capacity. In other words, as you charge it, the Voltage increases and discharge, voltage decreases in a linear way. Also they self discharge far too fast for long term energy storage.
The Super Capacitor battery is still a Lead Acid battery, but they use part of the technology that is used in a super capacitor. Its cell construction contains a standard lead-acid battery positive electrode and standard sulphuric acid electrolyte. The Super capacitor part is a specially prepared negative carbon-based electrode that stores electrical energy via double layer capacitance. It is this Carbon electrode that provides the protection from sulfation, when the Battery is partially charged/discharged, as well as the other significant benefits in performance.  The resulting cell performs with characteristics beyond either a lead-acid cell or a supercapacitor, with charge and discharge rates, cycle life, efficiency and performance all enhanced. The Battery is more commonly known as the Carbon Foam, or Lead Carbon Battery. An Ozy conpany coined the Super Capacitor for their design.

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17 hours ago, Knot Me... maybe said:

have a 35amp AGM battery that's been raced, rallied, rolled and generally treated like sh*t for the best part of easy 10 and quite possibly nudging 15 years. It still holds a perfect charge for months on end untouched. Often sucked bone dry (I use it to power a hooka) and hardly ever topped up using big grunt or smart grunt, often just jumper leads off the house bank or via older school solar only.

The thing is a genuine frea

There always has to be one that makes a mockery of us Nerds 😁
I was talking to a Boaty once about all the nerdy stuff about Batteries and Charging and getting the most out if them and he too replied with, well I just have a simple start battery and it gets abused daily and yet it is now well over 10yrs old and still performing just fine. Kind of blows my discussion out of the water when that happens.

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am not a fan of lithium batteries on a boat

this is why

https://www.tvnz.co.nz/one-news/new-zealand/glider-pilots-battery-caught-fire-mid-flight-causing-fatal-2017-crash-in-northland

they always blame the charging......but personally i think there is something else going on that they don't yet understand

https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems

 The enclosure Boeing had to add is 185 lb (84 kg) heavier, negating the lighter battery potential.[61]

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18 minutes ago, erice said:

"At the time of the crash, it was the only battery-powered glider in New Zealand."

You'd have to assume they won't be selling too many more here in the near future. 

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3 hours ago, erice said:

am not a fan of lithium batteries on a boat

this is why

https://www.tvnz.co.nz/one-news/new-zealand/glider-pilots-battery-caught-fire-mid-flight-causing-fatal-2017-crash-in-northland

they always blame the charging......but personally i think there is something else going on that they don't yet understand

https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems

 The enclosure Boeing had to add is 185 lb (84 kg) heavier, negating the lighter battery potential.[61]

 

There are many many different types of lithium batteries available,  just stating that they are all bad in a sweeping statement doesn't make much sense.   The battery types they are quoting are lithium polymer batteries,  these have massive current draw capacity...I have seen Lithium polymer capable of a 100c discharge and have some of the highest energy v weight densities avalible...which is why they are in aircraft...But this amazing performance comes at a cost of them being extremely volatile and cell balance needs to be perfect. But they won't just catch on fire,  something in the system need to fail for that to happen and once that happens because the electrolyte is a hydrocarbon....petrol and diesel are hydrocarbons.  There is nothing magical going on that they don't understand with these batteries,  it will be a fault with the system looking after them as in the Boeing article they mention dendrites and these will form when a cell is over charged. 

Also these as with other lithium batteries they don't like to be fully charged and are happiest between 40 - 80% charged.  

The Lithium variant that are used on boats and generally all mobile applications are Lithium Iron Phosphate,  these are not capable of thermal run away.   They just die slowly and quietly with little fuss is not managed well.  You can shot them and almost nothing happens.  They are also by far safer than any of the lead acid battery family that you will have on your boat currently, Gel, Agm and flooded lead acid being the worst for safety [there are others].

 

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so the lithium iron phosphate batteries you speak of are not the lithium ion batteries that thermally ran away and caused these problems 4 years ago?

https://www.nytimes.com/2016/09/03/technology/samsungs-recall-the-problem-with-lithium-ion-batteries.html

https://www.cnet.com/news/why-are-hoverboards-exploding-and-catching-fire/

some good info here

Lithium Iron Phosphate (LiFePO4)
Lithium iron phosphate (LFP) has a lower specific energy and lower cell voltage than other cathode materials, it has the benefit of being very stable, which gives excellent cycle life and high specific power with much lower risk of thermal runaway, even if abused. This makes it the safest of the LI cathode chemistries currently on the market.
LFP are generally used in stationary systems. They are being used to replace lead-acid starting batteries in vehicles. Four LFP cells in series provide 12.8 volts, compared with a standard lead-acid battery 13.8 volts. There is some question as to how LFP batteries will fair in the long term as regular vehicle charging systems are designed to charge the battery at 14.4 volts continuously in operation (BU-205, 2018).

https://www.fireandemergency.nz/assets/Documents/Files/Report_174_Lithium_Batteries_Whats_the_problem.pdf

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